➕ 8th Grade Math · Unit 2
Transformations and Congruence
20 short narrated lessons in 4 chapters, each with pictures, a quiz with a hint and a second try, and an explanation for every answer.
Standards: 8.G.A.1 8.G.A.3 8.G.A.2 8.G.A.4 8.G.A.5
What your child will learn
Rigid transformations
- TranslationsSlide a figure on the coordinate plane and describe how the coordinates change.
- ReflectionsFlip a figure over the x axis or y axis and describe how the coordinates change.
- RotationsTurn a figure ninety or one hundred eighty degrees around the origin and describe how the coordinates change.
- What Rigid Motions PreserveVerify that rigid motions keep lengths, angle measures and parallel lines the same.
- Rigid Transformations Review ReviewReview translations, reflections and rotations and what they preserve.
Congruence
- Congruent FiguresExplain that two figures are congruent when one can be moved onto the other with rigid motions.
- Sequences of Rigid MotionsDescribe a sequence of translations, reflections and rotations that maps one figure onto another.
- Proving Figures Are CongruentDecide whether two figures are congruent and justify the answer with transformations.
- Congruence Review ReviewReview congruent figures and describing sequences of rigid motions.
Dilations and similarity
- DilationsEnlarge or shrink a figure from a center using a scale factor.
- Dilations on the coordinate planeDilate a figure from the origin by multiplying each coordinate by the scale factor.
- Similar figuresExplain that two figures are similar when one can be turned into the other by rigid motions and a dilation.
- Showing figures are similarDescribe a sequence of transformations that shows two figures are similar.
- Dilations and similarity review ReviewReview dilations, scale factors and showing figures are similar.
Angles in triangles and parallel lines
- Parallel Lines and TransversalsIdentify equal angles formed when a transversal crosses parallel lines.
- The Triangle Angle SumExplain why the angles of any triangle add to one hundred eighty degrees using parallel lines.
- Exterior Angles of TrianglesShow that an exterior angle of a triangle equals the sum of the two far interior angles.
- Angle-Angle SimilarityExplain why two triangles with two pairs of equal angles are similar.
- Angles in Triangles and Parallel Lines Review ReviewReview parallel line angles, triangle angle sums, exterior angles and angle-angle similarity.
- Unit 2 test: Transformations and CongruenceShow what you learned in the whole unit (Rigid transformations, Congruence, Dilations and similarity, Angles in triangles and parallel lines) by answering mixed questions.
Try a question from this unit
From the lesson “Translations”
Point K(2, −5) is translated 4 units left and 3 units up. Where is its image, K'?
Show the answer
(−2, −2). Moving left subtracts from x, so 2 becomes −2, and moving up adds to y, so −5 becomes −2. The choice (6, −2) moves right instead of left.
Hint kids see after a wrong try: “Left and right moves change only one coordinate, and up and down moves change the other. Decide which grows and which shrinks.”
Key words
- translation
- image
- reflection
- line of reflection
- rotation
- center of rotation
- rigid motion
- preserve
- congruent
- sequence
- map
- justify
- dilation
- scale factor
- center of dilation
- similar
- corresponding
- transversal
- alternate interior angles
- corresponding angles
- angle sum
- exterior angle
- remote interior angles
- angle-angle similarity
Try these lessons in Kids Shelf
Narrated lessons, pictures and quizzes for every grade from K to 8. Works offline.
